Buckles are widely employed on various apparels and articles, such as backpacks, to detachably connect two ends of a fastening belt. Such buckles usually include a male and a female member connected to the two ends of the fastening belt. By engaging or disengaging the male and female members with or from each other, or depressing or releasing a push element, the two ends of the fastening belt could be connected or separated under control. In addition to control the connection or separation of the two ends of the fastening belt, the buckle also serves as a major supporting means when the fastening belt is subjected to an external force.
In a conventional low-profile buckle, the male member typically includes a plug head portion and the female member a receiving space corresponding to the plug head. The plug head portion includes two spaced elastic arms, which elastically shift inward when entering the receiving space of the female member and elastically spring into two side openings formed on two side walls of the receiving space to firmly hold the male member to the female member. When it is desired to open the buckle, simply apply two opposite inward forces on the two elastic arms exposed from the side openings to cause separation of the elastic arms from the side openings, and then pull the male member out of the female member.
A main force-bearing structure on the conventional low-profile buckle to prevent the connected male and female members from unexpected separation from each other includes the two elastic arms of the male member and two end wall surfaces of the two side openings closer to a front end of the female member for the two elastic arms to abut thereon. Since the two elastic arms elastically exposed from the side openings are subject to inward compression and deformation to easily separate from the end wall surfaces of the side openings, the buckle tends to open unexpectedly to cause inconveniences.